The present invention relates to photographic printers. In particular, the present invention relates to a photographic printer of the variable working distance type which uses external print paper supply and take-up magazines.
Photographic printers produce color or black and white prints or transparencies from photographic film originals (generally negatives). High intensity light is passed through the film and imaged on the photosensitive print medium (film or paper). The photographic emulsion layers on the print paper or film are exposed and subsequently processed to produce a print of the scene contained in the original.
Photographic printers have been developed which utilize supply and take-up magazines or casettes for photographic paper. This permits paper to be supplied and removed from the photographic printer without turning off all lights. Printers using magazines include the Pako Mach II, Kodak 2610, and Agfa 7560 high speed printers. In some cases, the magazines are large enough to accomodate rolls of paper up to 500 meters long.
In general, the printers which use external supply and take-up magazines have been "fixed working distance" rather than "variable working distance" printers. In other words, the distance between the negative plane and the paper plane is a fixed distance. In order to vary the magnification and therefore vary the print size, the printers have provided for some adjustment of the position of the focusing lens and for the use of interchangeable lenses for each film print size combination.
The use of interchangeable lenses for different print sizes has obvious disadvantages. Most importantly, since lenses of the required size and optical quality are expensive, the use of a large number of interchangeable lenses to accomodate the various possible film/print size combinations significantly increases the cost of the printer. In addition, any change in print sizes and formats from the sizes and formats being used may necessitate purchasing a new lens.
Variable working distance photographic printers have been developed and are in use at the present time. An example of a variable working distance photographic printer is shown in co-pending application Ser. No. 776,876 filed Mar. 11, 1977, and assigned to the same assignee as the present application. In this type of printer, both the distance between the negative plane and the lens and the distance between the negative plane and the paper plane is variable. This is achieved with a fixed negative plane by making the positions of both the lens and the paper deck adjustable.
The variable working distance printers, however, typically have not used external supply and take-up magazines, and have typically involved printers having rather small paper rolls. The support and movement of the paper deck becomes extremely difficult when very large amounts of paper have to be moved with the paper deck.